Steer axle assembly

ABSTRACT

A steer axle assembly in accordance with the present invention includes an axle beam defining a first boss with a first bore. The assembly further includes a knuckle body that defines a second boss. The second boss is in the form of a unitary sleeve from which a tie rod arm and steering arm extend. The second boss includes a second bore. The assembly further includes a set of bearings disposed in one of the first and second bores. In one embodiment of the invention, the bearings are disposed in the axle beam bore. In another embodiment of the invention, the bearings are disposed in the bore defined by the knuckle body. The assembly finally includes a kingpin. The kingpin is rotatably received within the bore having the bearings and is rigidly coupled within the bore that does not include the bearings. The kingpin may be tightened to its required specification via the use of a washer and nut on one end of the kingpin.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] This invention relates to steer axle assemblies and moreparticularly to a two boss steer axle assembly incorporating bearings toallow rotation of the kingpin.

[0003] 2. Discussion of the Background Art

[0004] In a conventional steer axle assembly, a steering knuckleprovides a spindle or bearing support for a wheel hub, bearings andwheel assembly. The steering knuckle is coupled to the steer axle usinga kingpin. Typically, the steering knuckle has a forked yoke thatdefines first and second bosses with aligned bores. The yoke surroundsone end of the steer axle which defines a third boss having another borealigned with the bores of the knuckle yoke. The kingpin extends throughone of the knuckle bores, through the axle bore, and through theremaining knuckle bore to couple the knuckle and steer axle together.

[0005] In these conventional steer axle assemblies, the kingpin isfixedly coupled to the axle boss such that the kingpin does not rotatein relation to the axle boss. The knuckle pivots about the kingpin on avertical steering axis. Typically, bushings are disposed within thealigned bores of the knuckle to allow the knuckle to rotate relative tothe kingpin.

[0006] Conventional steer axle assemblies suffer from severaldisadvantages. First, conventional steer axle assemblies allow arelatively large amount of axial and radial movement of the kingpin. Asa result of this axial and radial movement, the kingpin joints aresubject to greater wear, thereby creating greater clearances andpermitting the kingpin to shift and oscillate within the knuckle boresand reducing the useful lives of the assembly components. In order tolimit axial and radial movement of the kingpin, shimming and precisionmachining of the steer axle assembly members are often required. Second,the use of a knuckle having a yoke (i.e., two bosses): (i) requires arelatively large number of seals; (ii) increases tooling, manufacturing,and assembly costs due to the relatively complex design; (iii) minimizesthe ability to adjust the drop of the steer axle from the spindle; (iv)increases the size and weight of the assembly; and (v) prevents apredictable and relatively narrow tolerance range of bearingpre-load/endplay because assembly and vehicle loading causes deflectionof bearings disposed within the bosses. Third, the use of bushings inconventional steer axle assemblies results in relatively largetolerances and often requires broaching or reaming of the bushings.

[0007] There is thus a need for a steer axle assembly that will minimizeor eliminate one or more of the above-mentioned deficiencies.

SUMMARY OF THE INVENTION

[0008] The present invention provides a steer axle assembly.

[0009] A steer axle assembly in accordance with the present inventionincludes an axle beam defining a first boss with a first bore. Theassembly further includes a knuckle having a body that defines only asecond boss as compared to the conventional knuckle that defines secondand third bosses. The second boss is in the form of a unitary sleevefrom which a tie rod arm and steering arm extend. The second bossincludes a second bore. The assembly further includes a set of bearingsdisposed in one of the first and second bores. In one embodiment of theinvention, the bearings are disposed in the axle beam bore. In anotherembodiment of the invention, the bearings are disposed in the boredefined by the knuckle body. The assembly finally includes a kingpin.The kingpin is rotatably received within the bore having the bearingsand is rigidly coupled within the bore that does not include thebearings. The kingpin may be tightened to its required specification viathe use of a washer and nut on one end of the kingpin.

[0010] A steer axle assembly in accordance with the present inventionrepresents a significant improvement as compared to conventional steeraxle assemblies. First, axial and radial movement of the kingpin isdiminished because such movement can be easily and consistentlymonitored and adjusted—without shimming or precision machining. Second,the two boss system of the inventive assembly provides for a simplifiedknuckle design and manufacture. The use of two bosses as opposed tothree also provides: (i) improved life of the joint because of thedecrease in the number of seals and necessary adjustments; (ii)decreased tooling, manufacturing and assembly costs; (iii) the abilityto easily change the kingpin length and/or spacer size to change thedrop in the axle beam thereby reducing the need for multiple gooseneckbeam forgings with different gooseneck drops from the spindle to thebeam spring pad or center section; (iv) a reduction in the overall sizeand weight of the assembly with the ability to accommodate a variety ofbrake styles and positions; (v) the ability to obtain a predictable andnarrow tolerance range or bearing pre-load/endplay; and (vi) the abilityto use structural steel of various cross-sections in addition to forgedbeams. Finally, the use of bearings, as opposed to bushings, within theboss bores provides: (i) the ability to obtain finer tolerances; (ii) areduction in the variation in joint movement; and (iii) lowermaintenance and manufacturing costs.

[0011] These and other features and objects of this invention willbecome apparent to one skilled in the art from the following detaileddescription and the accompanying drawings illustrating features of thisinvention by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a sectional and elevational view of a steer axleassembly in accordance with a first embodiment of the present invention.

[0013]FIG. 2 is a sectional and elevational view of a steer axleassembly in accordance with a second embodiment of the presentinvention.

[0014]FIG. 3 is a sectional and elevational view of a steer axleassembly in accordance with the first embodiment of the presentinvention illustrating a different configuration for the kingpin.

[0015] FIGS. 4-7 are sectional and elevational views of a steer axleassembly in accordance with the first embodiment of the presentinvention illustrating the use of various bearing configurations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Referring now to the drawings wherein like reference numerals areused to identify identical components in the various views, FIG. 1illustrate a steer axle assembly 10 in accordance with a firstembodiment of the present invention. Assembly 10 is configured for usein large trucks, but may find application in a wide variety of vehicles.In accordance with the present invention, assembly 10 includes an axlebeam 12, a knuckle 14, a kingpin 16, and a set of bearings 18. Assembly10 may also include a spacer 20, a nut 22, and a washer 24.

[0017] Axle beam 12 is provided to support a vehicle (not shown) onwheels (not shown) disposed proximate either end of beam 12. Beam 12 maybe made be from steel and may be forged or fabricated. Each end (onlyone of which is shown in FIG. 1) of beam 12 defines a first boss 26. Inthe illustrated embodiment, boss 26 forms the lower boss (i.e., the bossthat is closer to ground) of the two-boss assembly 10. This constructionfacilities the use of straight beams made of structural steel of variouscross-sections in addition to conventional forged I-beams (generallyhaving a gooseneck) because the drop of the axle beam may be variedthrough the size of kingpin 16 and/or spacer 20 rather than the axlebeam as described hereinbelow. Boss 26 includes a bore 28 extendinggenerally vertically and substantially perpendicular to the longitudinalaxis of beam 12. Bore 28 is configured to receive kingpin 16.

[0018] Knuckle 14 is provided for mounting of a wheel (not shown) of thevehicle and for connecting axle beam 12 and the steering components ofthe vehicle. Knuckle 14 may be made from steel and may be forged orfabricated. Knuckle may include a body 30, steering and tie-rod arms 32,34, a spindle 36, and a brake mounting plate 38.

[0019] Body 30 provides structural support for the other components ofknuckle 14 and defines a second boss 40 for receipt of kingpin 16. Boss40 is in the form of a unitary sleeve from which steering and tie-rodarms 32, 34 extend and includes a bore 42 configured to receive kingpin16. The angle of axle bore 28 and knuckle bore 42 are such to positionkingpin 16 generally vertically, preferably at some angle inboard from avertical position to assist steering.

[0020] Arms 32, 34 are provided to couple knuckle 14 to the steeringmechanism of the vehicle and to a support rod (not shown) extendinggenerally parallel to beam 12. Arms 32, 34 are conventional in the artand—as illustrated in FIG. 1—may be integral with body 30.Alternatively, arms 32, 34 may be bolted onto body 30 or connected via atapered fist or other conventional arrangement. In the case wherein arms32, 34 are made integral with body 30, arms 32, 34 may initially extendin a directly parallel to spindle 36 as knuckle 14 is formed and then beurged into their respective final positions. Spindle 36 is provided tomount a wheel (not shown) of a vehicle on wheel bearings (not shown).Spindle is conventional in the art and may be formed integral with body30.

[0021] Braking mounting plate 38 is provided to support a brake (notshown) for a wheel. Plate 38 may be integral with body 30 of knuckle 14or may be attached to knuckle 14 in a variety of conventional ways. Theinventive assembly 10 facilitates the use of a wide variety of brakes.For example, plate 38 may comprise a conventional round flange.Alternatively plate 38 may be formed so as to receive various air discor hydraulic brakes.

[0022] Kingpin 16 is provided to couple knuckle 14 to beam 12. Kingpin16 may be made from steel or other conventional metals or metal alloys.Kingpin 16 has a first portion rotatably supported by bearings 18 withinbore 42 of knuckle body 30 and a second portion fixedly coupled withinbore 28 of beam 12. Referring to FIG. 2, in a steer axle assembly 10′ inaccordance with a second embodiment of the present invention, kingpin 16has a first portion rotatably supported by bearings 18 within bore 28 ofbeam 12 and a second portion fixedly coupled within bore 42 of knucklebody 30. Kingpin 16 may be fixedly coupled within bore 28 of beam 12 (orbore 42 of knuckle body 30 in the case of assembly 10′) in aconventional manner through the-use of one or more drawkeys.

[0023] Referring again to FIG. 1, kingpin 16 has a longitudinal body 44disposed about an axis 46 with a first axial end defining an end flange48 and a second axial end defining a partially threaded shank 50. Flange48 extends radially outwardly from body 44 and is disposed against beam12 adjacent the end 52 of bore 28 closest to ground. Shank 50 extendsfrom body 44 in the direction of axis 46 and has a diameter that is lessthan the diameter of body 44. Shank 50 extends outwardly from end 54 ofbore 42 of knuckle body 30. Referring to FIG. 3, in an alternateembodiment of a steer axle assembly 10″ in accordance with the presentinvention, flange 48 may be disposed against bearings 18 adjacent end 54of bore 42 and shank 50 may extend outwardly from end 52 of bore 28 ofbeam 12.

[0024] Bearings 18 are provided to allow relative rotation betweenkingpin 16 and either knuckle 14 (in assembly 10) or beam 12 (inassembly 10′). In the case of assembly 10′—where bearings 18 aredisposed in the lower boss 26 (i.e., the boss that is closer toground—bearings 18 may comprise conventional wheel bearings because theshort distance between bearings 18 and ground as compared toconventional steer axle assemblies reduces the load required duringbraking of the vehicle. Bearings 18 may take one a variety of forms.Referring to FIG. 1, bearings 18 may comprise a unitized or cartridgebearings sold under the trademark “UNIPAC” by Timken Corp. Bearings 18includes first and second bearing cones 56, 58 with cones 56, 58adjacent to one another. Cones 56, 58 form inner bearing races andprovide a bearing surface for kingpin 16. Bearings 18 further include aunitary bearing cup 60 disposed radially outwardly of both cone 56 andcone 58 and forming a pair of outer bearing races. Cup 60 is sized so asto be received within bore 42 of knuckle body 30 (or, bore 28 of beam 12in the case of assembly 10′ in FIG. 2). Alternatively, cup 60 may bemade integral with knuckle body 30.

[0025] Referring to FIG. 4, another alternative set of bearings 18′ foruse within the inventive steer axle assemblies is illustrated. Bearingset 18′ may comprise a wide-spread version of the unitized or cartridgebearings illustrated in FIG. 1. Bearing set 18′ includes first andsecond bearing cones 62, 64 separated by a spacer 66. Cones 62, 64 forminner bearing races and provide a bearing surface for kingpin 16.Bearings 18′ further include a unitary bearing cup 68 disposed radiallyoutwardly of both cone 62 and cone 64 and spacer 66 and forming a pairof outer bearing races. Cup 68 is sized so as to be received within bore42 of knuckle body 30 (or, bore 28 of beam 12 in the case of assembly10′ in FIG. 2). Alternatively, cup 68 may be made integral with knucklebody 30.

[0026] Referring to FIG. 5, an alternative set of bearings 18″ for usewithin the inventive steer axle assemblies is illustrated. Bearing set18″ may comprise the manually adjusted bearings having model number 2T-Sand manufactured by Timken Corp. Bearings 18″ includes first and secondbearing cones 70, 72 that are separated from one another along axis 46.Cones 70, 72 form inner bearing races and provide a bearing surface forkingpin 16. Bearings 18″ further include bearing cups 74, 76 disposedradially outwardly of cones 70, 72, respectively and forming a pair ofcorresponding outer bearing races. Cups 74, 76 are sized so as to bereceived within bore 42 of knuckle body 30 (or, bore 28 of beam 12 inthe case of assembly 10′ in FIG. 2).

[0027] Referring to FIG. 6, yet another alternative set of bearings 18′″for use within the inventive steer axle assemblies is illustrated.Bearing set 18′″ may comprise the pre-set bearings having model number2T-S and manufactured by Timken Corp Model. Bearing set 18′″ includesfirst and second bearing cones 78, 80 that are separated from oneanother along axis 46. A spacer 82 is disposed between cones 78, 80.Cones 78, 80 form inner bearing races and provide a bearing surface forkingpin 16. Bearings 18′″ further include bearing cups 84, 86 disposedradially outwardly of cones 78, 80, respectively and forming a pair ofcorresponding outer bearing races. Cups 84, 86 are sized so as to bereceived within bore 42 of knuckle body 30 (or, bore 28 of beam 12 inthe case of assembly 10′ in FIG. 2).

[0028] Referring to FIG. 7, yet another alternative set of bearings 18″″for use within the inventive steer axle assemblies is illustrated.Bearing set 18″″ may comprise the bearings sold under the trademark“WHEELPAC” by Timken Corp. Bearing set 18″″ includes first and secondbearing cones 88, 90 with cones 88, 90 adjacent to one another. Cones88, 90 form inner bearing races and provide a bearing surface forkingpin 16. Bearing set 18″″ further includes bearing cups 92, 94disposed radially outwardly of cones 88, 90, respectively and forming apair of corresponding outer bearing races. Cups 92, 94 are sized so asto be received within bore 42 of knuckle body 30 (or, bore 28 of beam 12in the case of assembly 10′ in FIG. 2). Although FIGS. 4-7 illustratevarious bearing sets disposed within bore 42 of knuckle body 30, itshould be readily understood by those of skill in the art that theillustrated bearings could alternatively be disposed in bore 28 of beam12 as illustrated in FIG. 2.

[0029] Referring again to FIG. 1, spacer 20 is provided to maintain apredetermined distance between beam 12 and knuckle 14. Spacer 20 isconventional in the art and may be made from conventional metals orother solid materials. Spacer 20 is annular and the inner diameter issized to receive kingpin 16. One side of spacer 20 is configured toengage bearings 18. An opposite side of spacer 20 is configured toengage beam 12 (or knuckle body 30 in the case of assembly 10′ in FIG.2). The axial length of spacer 20 may be varied in order to vary thedrop of beam 12.

[0030] Nut 22 and washer 24 are provided to enable the application of aninitial bearing pre-load to the kingpin joint. Nut 22 and washer 24 maybe made from conventional metals and are sized to receive shank 50 ofkingpin 16. Nut 22 and washer 24 may be combined into a one-pieceflanged nut. Washer 24 is disposed about an unthreaded portion of shank50. Turning nut 22 produces a predefined bearing pre-load acting throughwasher 24, bearings 18 (which may comprise one or more bearing conesand/or spacers depending upon the bearing set used), spacer 20, beam 12(or knuckle body 30 in the case of assembly 10′ in FIG. 2) and endflange 48. As set forth hereinabove, in each of the bearings 18, 18′,18″, 18′″, 18″″ disclosed herein, both bearing rows are disposed withina single boss 40 of knuckle 14 (or boss 26 of beam 12 in the case ofassembly 10′). As a result, a predictable and narrow tolerance range ofbearing pre-load/end play can be obtained by tightening nut 22. In aconventional three-boss steer axle assembly, the bearing rows aredisposed in separate bosses on the knuckle body and deflection occursduring assembly and under vehicle static and dynamic load therebyprecluding the ability to obtain and retain narrow tolerances. Nut 22and washer 24 may be disposed within an enclosure cap (not shown)coupled to knuckle 14.

[0031] As described and illustrated hereinabove, a steer axle assemblyin accordance with the present invention represents a significantimprovement as compared to conventional steer axle assemblies. First,the arrangement allows easy application of an initial bearing pre-loadby tightening nut 22. As a result, axial and radial movement of kingpin16 is reduced without shimming or precision machining. Second, thesingle boss knuckle 14: (i) improves the life of the kingpin jointbecause only a single set of seals are needed; (ii) decreases tooling,manufacturing and assembly costs because of the simple design of theknuckle; (iii) enables a relatively easy adjustment of the axle beamdrop through variation in the length of the kingpin 16 and/or spacer 20thereby reducing or eliminating the need to have multiple beam forgingswith different gooseneck drops from the spindle to the spring pad orcenter section of beam 12; (iv) reduces the overall size and weight ofthe assembly; (v) accommodates a variety of brake styles and positions;(vi) provides the ability to obtain a predictable and narrow tolerancerange of bearing pre-load/endplay; and (vii) facilitates the use ofstructural steel beams of various cross-sections in addition to forgedbeams. Finally, the use of bearings 18, as opposed to bushings, withinthe boss bores 28, 42 provides: (i) the ability to obtain finertolerances; (ii) a reduction in the variation in joint movement; and(iii) lower maintenance and manufacturing costs.

[0032] It is to be understood that the above description is merelyexemplary rather than limiting in nature, the invention being limitedonly by the appended claims. Various modifications and changes may bemade thereto by one of ordinary skill in the art which embody theprinciples of the invention and fall within the spirit and scopethereof.

I claim:
 1. A steer axle assembly, comprising: a steer axle beamdefining a first boss, said first boss having a first bore; a knucklehaving a body that defines a second boss in the form of a unitary sleevefrom which a steering arm and a tie rod arm extend, said second bosshaving a second bore; a set of bearings disposed within one of saidfirst and second bores; and, a kingpin having a first portion supportedby said bearings in said one bore and a second portion fixedly coupledwithin another of said first and second bores.
 2. The assembly of claim1 wherein said set of bearings includes first and second bearing conesand a spacer disposed between said first and second bearing cones. 3.The assembly of claim 1 wherein said set of bearings includes first andsecond bearing cones and a unitary bearing cup disposed radiallyoutwardly of said first and second bearing cones.
 4. The assembly ofclaim 1 wherein said set of bearings includes first and second bearingcones adjacent one another.
 5. A steer axle assembly, comprising: asteer axle beam defining a first boss, said first boss having a firstbore; a knuckle having a body that defines a second boss in the form ofa unitary sleeve from which a steering arm and a tie rod arm extend,said second boss having a second bore; a set of bearings disposed withinsaid first bore; and, a kingpin having a first portion supported by saidbearings in said first bore and a second portion fixedly coupled withinsaid second bore.
 6. The assembly of claim 5 wherein said bearingsinclude first and second bearing cones and a spacer disposed betweensaid first and second bearing cones.
 7. The assembly of claim 5 whereinsaid set of bearings includes first and second bearing cones and aunitary bearing cup disposed radially outwardly of said first and secondbearing cones.
 8. The assembly of claim S wherein said set of bearingsincludes first and second bearing cones adjacent one another.
 9. Theassembly of claim 5, further comprising a spacer disposed between saidbearings and said knuckle.
 10. The assembly of claim 5, furthercomprising: a nut; and, a washer wherein said kingpin includes a firstend defining a flange and a second end defining a shank and said nut andsaid washer are disposed about said shank.
 11. The assembly of claim 10wherein said flange is disposed against said knuckle and said washer isdisposed against said bearings.
 12. The assembly of claim 10 whereinsaid flange is disposed against bearings and said washer is disposedagainst said knuckle.
 13. A steer axle assembly, comprising: a steeraxle beam defining a first boss, said first boss having a first bore; aknuckle having a body that defines a second boss in the form of aunitary sleeve from which a steering arm and a tie rod arm extend, saidsecond boss having a second bore; a set of bearings disposed within saidsecond bore; and, a kingpin having a first portion supported by saidbearings in said second bore and a second portion fixedly coupled withinsaid first bore.
 14. The assembly of claim 13 wherein said bearingsinclude first and second bearing cones and a spacer disposed betweensaid first and second bearing cones.
 15. The assembly of claim 13wherein said set of bearings includes first and second bearing cones anda unitary bearing cup disposed radially outwardly of said first andsecond bearing cones.
 16. The assembly of claim 13 wherein said set ofbearings includes first and second bearing cones adjacent one another.17. The assembly of claim 13, further comprising a spacer disposedbetween said bearings and said axle beam.
 18. The assembly of claim 13,further comprising: a nut; and, a washer wherein said kingpin includes afirst end defining a flange and a second end defining a shank and saidnut and said washer are disposed about said shank.
 19. The assembly ofclaim 18 wherein said flange is disposed against said axle beam and saidwasher is disposed against said bearings.
 20. The assembly of claim 18wherein said flange is disposed against bearings and said washer isdisposed against said axle beam.